Process for overcoating granular materials

Abstract

A process for overcoating granules with overcoating material in a granulator by providing the inside surface of the granulator, before introduction of the granules, with a layer of the overcoating material in a thickness of 0.1 to 1 mm, maintaining a preset entrainment height of the granules during the granulation process, and adding the overcoating material in the flowing particle bed. The deposited layers are very uniform.

We claim: 
     
       1. A process for overcoating coated fuel particles with binder-containing graphite powder for high-temperature reactors comprising adding to the inside surface of a rotatable granulator adapted to provide a flowing particle bed, before introduction of the granules, a layer of overcoating material, intended to overcoat said granules, in a thickness of 0.1 to 1 mm, maintaining a present entrainment height of the granules during subsequent granulation by varying the inclination and/or rotational speed of the granulator, and adding the covering material by pipe means immersed in the midst of the granules in a flowing particle bed. 
     
     
       2. The process according to claim 1, wherein the overcoating material is always added in a region of the flowing particle bed which, from the top, is located at a height of 0.2 to 0.5 of the total height of the flowing particle bed. 
     
     
       3. The process according to claim 1, wherein the covering material is added with a delivery pipe means which, viewed in front elevation, forms an angle alpha of 10° to 30° with the vertical and facing against the direction of rotation of the granulator.